Each mask comes with a multi-layer pm2.5 filter featuring 2 layers of meltblown filter and 1 layer of carbon activated fabric. Valved masks are suitable for biking, hiking, hazardous air quality, mold, dust, and environments for protection of the mask wearer not interacting with the public in proximity. For this reason, non-valved (not vented) masks are appropriate when in public places or in proximity of other people, in order to protect the mask wearer and others in the environment.